Brake shoe structure



March 6, 1934. R. J. NORTON 1,950,262

BRAKE SHOE STRUCTURE Filed Nov. 13, 1930 INVENTOR. Raymond J. Norfoo ATT RNEYS.

Patented. Mar. 6,. 1934 ssazez BRAKE SHOE Raymond J. Norton,

to Bendix Brake Comp corporation of Illinois Washington, D. C.

s'rauc'runn assignmany, South Bend, lint, 2.

Application November 13, 1930, Serial No. 495,532

3 Claims.

on facings, parribed in my co- 6l,0 l3.

This invention relates to frlcti ticularly those of the type descpending application, Serial No. 3

The usual type of brake com internal expanding shoe or an e ing strap towhich is attached Since the advent and high de servo and duo servo typesof brake, the coefiicient of friction of the friction facing has becomeof 30 paramount importance. Due to the accelerated response and largerpower multiplications of suchtypes of brakes, it has become desirable tochoose friction material having a relatively low coefficient offriction.

The purpose of the present invention is to provide a friction materialwhich is adapted to be attached or molded to the shoe, and which willpresent a surface having'the desirable hardenlng properties and inaddition a relatively low coemcient of friction.

The invention broadly comprehends the idea of utilizing the presentmaterials, that is to say, the materials now usually employed, and by asuitable treatment to reduce tne coemcientof friction below that whichwould normally obtain. For purposes of illustrating the invention in thedrawing Figure 1 is a perspective showing of 9. having a sectioncuttherefrom;

prises either an xternal contracta friction facing. velopment of thesection of lining and so Figure 2 is an enlar section of Figure 1. Morespecifically provision of a'friction mate efficient of friction which ispreferably made up by providing a permanently lubricated facing. Thismay be done by treating suitable fibrous material, such as asbestos,cellulose products, etc, with a suitable lubricant, and with thecomponents of a synthetic resin. Upon reaction of the go components of,the resin, in the manner well lmown to those skilled in the art, anini'usible substance may be produced which comprises a synthetic resinwith which lspermanently' incorpointed a predetermined amount, of alubricant. its shown in the drawing, the lining 1c may be formed of aplurality of layers oi fibrous mate rial l2 specially treated inaccordance with the process or processes hereinafter set forth in de=gement of a portion of the the invention includes the rial having a lowcoy be carried out by, treating relatively thin sheets of the fibrousmaterial and then building up a number of these to form an integrallaminated siz'ucture.

'Ihefriction material of the present invention 5'5 may be made upsimilarly to the manner dese The operation ma scribed in copendingapplication Serial No. 324,361, filed December 7, 1928, of which thepresent application is a continuation inpart.

As pointed out in that application, the preferred resin whichis employedis a condensation product of furfural and phenol. material is chosenbecause of its high reactivity, .ticularly the ease with whi in a metalmatrix.

In carrying out the invention, asbestos or other fibrous products of lowor negligible flammability may be treated by mixing the loose fiberswith a powder comprising a solid, non-oleaginous lubricant, such, forexample, as graphite, soapstone. talc, or'a combination of suchmaterials. From these fibrous products treated'with thepowdered llubricant, a felted or woven strip of filler material is made up. Ifdesired, such a strip may be made up from felted or woven asbestosalone, in which case the powdered lubricant is added to 76 the striplater, either in a dry powdered form, or carried by a suitable liquidvehicle that is subsequently evaporated or otherwise removed.

' After the initialtreatment of the filler material with the lubricatingsubstance, it may then 80 be treated with a solution of a fusible resinin a suitable vehicle or solvent. Y This solution also contains ahardener. As is known, upon the application of sufiicient heatandpressure to these potentially reactive substances, a further reactionensues with the formation of an infusible product.

The fusible form of the resin may'first be made up by reacting theproper amounts of furfural and phenol in the presence of a suitablecatalyst, such as hydrochloric acid. As in the usual case of making up afusible form of the resin, the amount of furfural formaldehyde, orequivalent substance which is eployecl, is inscient to form theinfusible resin. These substances are then allowed to react under theproper thermal conditions. After the fcrtion oi the fusible form of theresin, the water may be removed and the mass distilled with steam toremove the a 0 excess of phenol.

This fusible sum or resin may then be dissolved in a suitable solvent,such as alcohol, acetone, etc. To this solution of the resin there maythen be added a suitable quantity of a hardening agent, which will reactwith the fusible form of the resin to form the infusiblc product. Whenfurfural is employed the hardening agent may be an additional amount offurfural and ammonia, or furfuramld. In place of the furfurai, or itsde- 1 0 and parch it may be molded rivative, other hardeners, such ashexamethylenetetramin, paraform, etc., may be used.

While a furfural condensation product is given as a typical andpreferred form of invention, it is to be understood that this is merelyan example of any form of infusible synthetic resin. Instead of afurfural condensation product, there may be employed the phenolformaldehyde condensation or the acetylene condensation product.

The potentially reactive composition which comprises a solution of thefusible gum, with which is associated a suitable hardener, is then usedas an impregnant for the pretreated fibrous fillingv material. Theimpregnation of the fiber,

may be carried out under any of the well known accelerating conditions.'After the desired impregnation of the fiber has been accomplished, thematerial may then be placed in a mold and heated to initiate andaccelerate the final reaction, with the resultant formation of the hardset infusible resin. It will be understood that the quantity ofhardening agent employed, and the temperature and pressure conditions ofthe treatment may be varied, depending upon the degree of infusibilityand hardness which is de-. sired.

It will be understood that the material comprising a fibrous filler, asolid, comminuted and non-oleaginous lubricant, and a dispersedcondensation product may be molded directly on the brake shoe, as.pointed out in the copending application Serial No. 324,362, filedDecember I, 1928. Also, if desired, the facing may be made up as aseparate element, and then attached to the shoe by any suitable means.

After the described treatment, the resultant product comprisesapermanently lubricated resin. As already indicated, this may be made upin the form of relatively thin strips. \If such is the case, these maybe built up to the desired thickness and then treated with additionalquantities of the potentially reactive infusible form of the resin.

Upon the application of heat and pressure, the

- separate lamina: may be permanently bonded together. Also, if desired,the material may be made up initially of the desired thickness byimpregnating superimposed layers of'the fiber with the synthetic gum inthe plastic form. These several layers may then be subjected to heat andpressure in a mold to cause complete reaction and the formation of theinfusible product.

Other methods of combining the materials may be followed within thepurview of my invention. Thus the powdered or comminuted lubricant maybe mixed with the fusible resin and such mixture appliedto felted orwoven strips of fibrous material and the resin subsequently converted toan infusible form asabove described. Or, woven or felted strips ofasbestos may be treated with a fusible resin, then dusted with thepowdered lubricant, and the resin finally converted intoan infusibleform. If desired, the loose fibrous materials may be mixed with thepowdered lubricant and fusible resin to compose a material that may bemolded or cast into desired shapes and later treated to convert theresin into an infusible form.

While there are described several specific embodiments of the invention,it is to be understood that these are given merely by way of examplefor, as pointed out, the particular methods disclosed may be greatlymodified,.within the scope of the principles involved. Hence, it is notintended that the invention shall be limited to the descriptive matterset forth in the specificaiom. except as such limitations are clearlyimposed by the appended claims.

Iclaim:

1. A friction facing comprising a plurality of thin sheets of a fibrousmaterial each treated with a non-oleaginous lubricant and bonded with aresinoid. 11o 2. A friction facing comprising a plurality of thin sheetsof a fibrous material each treated with a powdered lubricant tohomogeneously disperse the lubricant through the sheets and permanentlybonded with an infusible synthetic resin.

3. A friction facing comprising thin sheets of a fibrous substance, eachsheet having permanently incorporated therewith a. predetermined amountof a non-oleaginous lubricant, the lubricant treated sheets then beingpermanently bonded together with an infusible synthetic resin.

RAYMOND J. NORTON.

